add directory study

study/linux-travel/minix-386/estdio21.tar/estdio21/_allocbuf.c

@@ -0,0 +1,53 @@
+/*                            _ a l l o c b u f                            */
+
+/* Malloc a buffer for a stream. Unbuffered streams use the built
+ * in buffers. Streams connected to terminals use small buffers.
+ */
+
+#include "stdiolib.h"
+
+/*LINTLIBRARY*/
+
+__stdiosize_t __allocbuf F1(register FILE *,fp)
+
+{
+  register int i;			/* pool scanner */
+
+  if (! TESTFLAG(fp, _IONBF)) {
+    fp->__bufsiz = BUFSIZ;
+
+    if (isatty(fileno(fp))) {
+      fp->__bufsiz = TTYBUFSIZ;
+      if (TESTFLAG(fp, _IOWRITE))
+	SETFLAG(fp, _IOLBF);
+    }
+
+#if	TTYBUFSIZ > BUFSIZ
+  << TTYBUFSIZE overruns BUFSIZ for buffer pool >>
+#endif
+
+    for (i = 0; i < POOLSIZE; i++) {
+      if (__iob[i] != NULL) {
+	fp->__base = __iob[i];
+	__iob[i]   = NULL;
+	SETFLAG(fp, _IOPOOLBUF);
+	goto Gotbuffer;
+      }
+    }
+
+    if ((fp->__base = (__stdiobuf_t *) malloc(BUFSIZ)) != NULL)
+      SETFLAG(fp, _IOMYBUF);
+    else {
+      CLEARFLAG(fp, (_IOFBF | _IOLBF));
+      SETFLAG(fp, _IONBF);
+    }
+  }
+
+  if (TESTFLAG(fp, _IONBF)) {
+    fp->__base   = &fp->__buf;
+    fp->__bufsiz = sizeof(fp->__buf);
+  }
+
+Gotbuffer:
+  return fp->__bufsiz;
+}